Lathe motor question and gloat..UPDATED NOT A GLOAT ANYMORE

Jeff Bower

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DSM, IA
Well, the motor on my lathe has decided to quit spinning. It's probably at least 35yrs old so it gave my grandpa and I a good run. It was/is a GE 1/2HP probably from a squirrel cage blower. The question I have is...It seems to work fine without the belt attached, but won't spin without a gentle push on the pully or not at all even without a blank loaded. It just groans as if the pully is to much resistance.:huh: Do older motors have brushes that can be replaced? Or is it somehthing else that could be repaired? I wouldn't mind using it to make a disk sander or something.:dunno:

Now for the gloat.....I'm picking up an older 1HP 1750RPM 115/220 Baldor with capacitor this weekend from a guy I met through craiglist for $40 so I set to upgrade DOUBLE from the 1/2HP I had before. I might ask some questions on wiring, and the possible jack shaft I might install later this week.
 
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If you need the extra power, it's hard to beat the price. But i think the 1/2hp motor might still have a lot of life left in it. There's a good chance it's a simple fix. The start capacitor may be shot, or it may have a lot of sawdust packed in it which is fouling the centrifugal switch. If it's a Repulsion start / Induction run (R.I.) motor, you may also have worn brushes or a fouled commutator. I'd start with the no-cost option - dirt. Most older motors are "open" with vent holes in the motor housing. This helps cool the motor, but also allows in sawdust and dirt.
The refusal to start spinning at all makes me think it's an induction motor (no brushes) with a fouled centrifugal switch, or a Repulsion start/Induction run motor with starter winding issues - probably the brushes. There could be other causes, but these seem the most likely to me, and they're easy to ferret out.
Since it's a lathe, the motor is probably either a capacitor start induction motor or an R.I. motor. You can tell the difference easily by looking for the telltale cylindrical tube (the capacitor) attached to the motor. Without that, it's probably an R.I. motor.

If you've never had a motor apart before, it may sound intimidating, but they're pretty straight forward. And, if it's already not working, what do you have to lose? The cleaning process, start to stop, should take 30 to 90 minutes. I'd start by marking the location of the rear bell housing to the main motor housing - marker, metal stamp, tape, etc. so that you reassemble things correctly. I'm assuming you have the motor on your workbench and unplugged. Remove the bolts or screws that hold the bell housing in place. On a motor that size, you've probably got 4 to deal with. I like to make sure there's enough clean space on my bench to lay out removed parts in an organized manner. Take pieces off carfully and set them asside deliberately so that you can reassemble everything in its proper order.
Once the bell housing screws are removed, you'll need to tap the bell housing off of the main housing. They're still held together with a friction grip. I like to use a wood block or broad flat blade screw driver to begin to drive the pieces apart with light taps working around the perimeter of the motor so that it all comes apart without wracking and binding.
Once the rear bell housing is off, you may be able to easily remove the armature (assuming you've already removed the pulley and any heavy dirt/corrosion fouling the shaft as it comes out of the other bell housing. If it comes out easily, remove it and set it aside. Now, you'll likely see decades of dirt packed in. I like an old toothbrush and a small paint brush or two to go after the dirt. Be carful poking anything rigid in there - you don't want to damage wiring. Once i get a good enough view of how things are arranged, i'll usually use a stick of wood to scrape off the large chunks. Occassionally, i'll use compressed air, but turn the pressure down to about 40 psi and wear eye protection. You may also inspect the centrifugal switch at this point to make sure it's clean and can move as it should along the shaft of the motor. There are different configurations, but they're pretty obvious to figure out when you're looking at them. Also, look for cracked, broken, or missing parts on this switch. There are springs and weights to account for. Any damage should be readily apparent.

You'll also want to take a minute to inspect the wiring connections to make sure things aren't cooroded or broken where you wire the cord to the motor. I'd also check the bearings to see that they don't have too much play or make any grinding or chatter noises.
Once it's all cleaned up and you've inspected the other items, reassemble the motor and give it a test.
I've "resurrected" a number of motors just with a good cleaning. Once i had a centrifugal switch that was sticking - a little cleaning brought it right back. The rest of the times, just getting rid of the dirt took care of the problem.
If the power cord looks iffy at all, i replace it. It's not always necessary, but it's only a few bucks, and there's no easier time to do it.
If things don't come back to life, take the capacitor with you to a motor repair place or an industrial supplier (Grainger, McMaster Carr, etc.) - they will test it for free before selling you a replacement. My last capacitor replacement was $7 - not expensive and easy to swap out.
I hope this helps some.
I hope others look this over to see where i may have left something out or may be missing something.
Have fun with it.
Paul Hubbman
 
I hope others look this over to see where i may have left something out or may be missing something.
Have fun with it.
Paul Hubbman

Paul, "left something out"?????? I doubt you did. Thanks so much for taking the time to write all that you did....I will try all that you mentioned. I didn't think about cleaning it out.:doh: Never occured to me that might be the problem. I've wanted to upgrade the motor anyway, so getting a 1HP motor for $40 seems like a no brainer to me, but hearing that a good cleaning may be all I need to use the motor again makes me feel good and I will have fun with it. As many of you know my grandpa made the lathe and putting the motor to another use would keep with his values of fixing something many times before you give up on it....he rebuilt a tiller motor problably a dozen times when I was young and used it for many more years than that.

thanks again. :)
 
Good Luck with the motor Jeff, Paul gave you a lot of options there.As for Grandpa he sounds like mine, never give up on anything, where there's a will there's a way. There's also a pile of motors and old tools in the to-do pile.
 
There's also a pile of motors and old tools in the to-do pile.

I resemble that comment. I just recently got the shop reasonable again. There are 3 motors that need work (a 1/3hp, a 1hp, and a 2hp - all R.I. motors), a lathe from the late 1800's (from my dad), an Atlas 8" table saw (for a friend of mine), a Craftsman / King Seeley jointer (also for a friend), a Companion 15" scroll saw (hopefully leaving soon), and the finishing touches on a table raising mechanism for my drill press.
I need to clear some clutter.
Paul Hubbman
 
I also have a 1/4HP motor that needs a new switch that I'm going to make buffer out of......someday.....been saying that for 6 months. The lathe motor will be fixed/installed this weekend though.Why am I so confident it will happen?....Hello, my name is Jeff and I'm a woodturner. It's been about 72 hours since my last lathe session.:eek::bonkers::bang::doh::bonkers:
 
Jeff, I'm kind of new to turning but it sounds like I've been where you are; I had a similar problem with my drill press motor; Dirt/dust was the culprit there. It just had NO power whatsoever all the sudden. I ended up just using compressed air very throroughly (probably not as safely as I coul've-my output is set at 95psi), but I luckily didn't damage anything, but certainly got more than a faceful of dust. i wasn't expecting there to be so much in there. Suffice to say that after I cleared my eyes and sneezed a couple times, the drill press worked good as new.


As for your lathe, I only got my lathe this fall, but I modified it in short order, swapping out the 1/2 hp motor for a 1.5HP leeson which I originally had put on my bandsaw as a replacement for the 3/4HP taiwanese motor on my ridgid 14" bandsaw. I ended up with a 2HP baldor with the spin-down brake that I don't know what to call it.

Anyway, I put the 1.5HP motor on a rockwell 46-111 and put a delta "jackshaft" pulley setup on it that I found on ebay for less than $50. I just put a couple of pieces of plywood across the back, and put some mounting blocks with a routered groove and wingnut bolts so that I could slide the entire assembly back and forth to use the factory step pulleys on the headstock. I have to also move the motor to do this, which is a PITA!!! But, its very worth having a 300rpm low speed vs. the 900 rpm that it was before I modded it. Try turning a large out of round blank at that speed and watch it walk around the floor by itself!!
 
Nathan, Thanks for the info...I don't suppose you have any pics of the jack shaft setup? :dunno: I'm more of a visual person and would really appreciate you posting them if you do.
 
Frustrating day so far....

Well, I got the new/old motor wired with a simple switch and a new power cord. It starts up just fine, but then either the power strip breaker or the breaker in the house box trips afte about 20 seconds??? :dunno: Any ideas as to why this would be happening? :huh: Remember I don't know much about eletrical stuff:eek:

I also took the old motor apart cleaned it, tried it again and it still just humms. I think it is done for good. :( That on top of shoveling about 4 inches of wet snow has made this not such a great sunday....
 
Well, I got the new/old motor wired with a simple switch and a new power cord. It starts up just fine, but then either the power strip breaker or the breaker in the house box trips afte about 20 seconds??? :dunno: Any ideas as to why this would be happening? :huh: Remember I don't know much about eletrical stuff:eek:

I also took the old motor apart cleaned it, tried it again and it still just humms. I think it is done for good. :( That on top of shoveling about 4 inches of wet snow has made this not such a great sunday....
A four pole (1725RPM) motor is not as efficient as a two pole motor but even at 50% efficiency you should draw less than 15 amps (for 1 HP). Try it on a different circuit and see if it will run there - see if you can find a circuit that's not in use by anything else at the time. If it trips the breaker there, you have a problem with excess current drain and have to find out whether it's just the way the motor works, or if you have a problem in the motor.

Regarding your old motor, if it just sits there and humms, the problem is almost certainly the starting circuit (if it will run when you give it a spin by hand). Replace the starting cap first.

Mike
 
Mike, I plugged the motor in with only the overhead light on in the garage. It ran for about 1 minute before it tripped the breaker in the house this time. I assume that means the motor is drawing to much current? :huh: Me thinks this might not be the motor for me? I have run my old 1/2 HP motor on the lathe, along with lights, aircompressor, and tv or radio without more than a slight dim of the light when the compressor turns on. This makes me think the motor is the problem and not my electrical setup for the garage. But then again...:dunno::huh::eek:

The guy I bought it from ended up only asking $25 for it, was $40 originally, when he found out I drove just over 30 miles to get it. So I'm not out that much if I can't get it to work, but right now I can turn and that is not good. He had no use for it and said, "if you can put it to good use I don't want more than $25". He hooked it up and ran it for about 2 minutes for me in his shop and it worked fine then?
 
I had a motor that was doing the same thing. What it turned out to be was the collar that slides along the shaft for the centrifugal switch was getting stuck. The result was that the start up circuit wasn't cutting out when the motor got up to speed. Cap start motors draw significantly more than their rated amperage during start-up. A one horse motor rated at 10 amps will be 20 or more when firing up. A 15 amp circuit can handle this for a short period because the circuit breakers are intentionally delayed. Everything may work fine on a 25 or 30 amp circuit - maybe even a 20 amp circuit with a short run and no load on the motor. It would definitely trip a 15 amp breaker after a short run.

I don't know if this is the problem with your motor, but it's probably worth investigating. If it's an open frame motor, you may be able to see the centrifugal switch inside the rear bell housing. If it's a drip proof or totally enclosed motor, I'd pull the rear bell housing off the motor and check the centrifugal switch to make sure everything moves easily. When the motor spins down, do you hear the switch click over? If not, the centrifugal switch is not working properly.

Then again, you may be off to the motor repair shop. As for the motor you had on the lathe, it may be the start capacitor. If you've got a motor repair shop in your area, you may take it in and have them check the capacitor. If that's not it, it may be the windings or the centrifugal switch.

Good luck with it.

Paul Hubbman
 
Thanks for your insight Paul. I did take the motor apart and cleaned out some bugs, dust and cobwebs and then put it back together. I didn't try it again, as I was tired of going inside, down to the basement and back out to the garage. With the blowing snow, me being frustrated and tired I was done for the night. I will try it again tonight and I have also located a couple of local motor repair places...will update when I know more.
 
Nathan, Thanks for the info...I don't suppose you have any pics of the jack shaft setup? :dunno: I'm more of a visual person and would really appreciate you posting them if you do.



I do have pics; sorry I haven't been online in a while. Here goes with the pics:



this is of the motor/jack shaft assembly; It is mounted on a piece of 3/4" plywood that is double bolted to the metal frame of the stand.

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Here's a closeup of the motor; It is a 1.5HP motor, to give some idea of scale. The pulley shown was incuded with the "jackshaft" setup; it replaces the 4 step pulley that came with the original motor of the lathe, which just happened to have the same size shaft (5/8") as the leeson 1.5HP motor I had. I forgot to take a pic of the motor mount, but it is mounted on a very sturdy shelf with "I" shaped supports screwed to it underneath to keep it from flexing under the weight of the motor, and hinged to a 2x4 that spans the back of the metal cabinet. The hinge is piano hinge, screwed in every inch and a half or so to be extra heavy duty. This motor must weigh at least 50-60 lbs. Just for clarification, the motor shelf is made of a piece of 3/4" birch plywood with 3/4" X 3" wide strips mounted as "I"'s under the board, perpendicular to the 2x4 that the shelf is mounted to. It just keeps the board from bending; I hope this makes sense.

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The last pic is a closeup of the jackshaft assembly, showing how I can shift it to the right or left to line up with the 4step pulley on the headstock of the lathe. This is a PITA, and not ideal, but it is a 3 to 1 reducing ratio, so much better than just starting out at the factory 900 RPM for the slowest pulley.


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I thought I'd add to your motor electrical issues. A 1HP motor usually draws between 12-14HP at full load.

When I ran a 3/4HP motor on a 15 AMP circuit, even with 12ga. wire, a 9.6A load from my bandsaw motor would trip the breaker when resawing, if I had more than a few lights on in the shed. That just wouldn't do. Circuits usually are rated for something like 75% of their maximum draw for a continuous load. So, theoretically, a long term 15A draw on a 20A circuit might trip the circuit. I replaced the motor with a 2HP baldor that draws more than 19.6 amps at full draw on a 110v circuit, or 9.8 amps at 220v. I've got a 20A 220V circuit now, running 10ga. wire, and I'm upgrading to a 50A circuit with 8ga. wire, so I can run my dust collector on 220v, with other 220v tools running at the same time.

I'd try your motor on another circuit in your house, as you're probably not going to get a full 1 HP motor to run continuously on that small of a circuit.
 
Nathan thanks for the pics of your jack shaft...I have found a local electrical shop that says they will give me a free estimate. Hopefully it can be fixed or maybe I can trade it to them for an old "fixed" one. Won't be til next week though as they have hours that don't fit well with my schedule. I think I might clean the garage this weekend just to get some shop time.....almost 2 weeks without a working lathe....I'm getting grumpy. :(
 
Still haven't got the 1HP motor looked at, shown in first pic, but I did hook up a 1/4HP motor that I had so I could calm my lathe withdrawls. Can't turn anything big, but its working. I made what can only be described as a crude jack shaft with pulleys and belts I had. It will need some tweeking, but I'm happy to be turning again.
 

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Very creative. Are those plane bearings?? That looks like a nice setup. I'll bet you can get the speed very low with the number of step pulleys there. Any news on what was wrong with the 1HP motor?

edit: just reread. Duh. You haven't gotten it looked at yet......





Just a side suggestion; a while back I got a brand new Baldor 2HP motor for about $70 because it'd been dropped and didn't run. One of the capacitors inside was cracked. I replaced it, thinking it couldn't hurt to start with the obvious. Long story short, brand new 2HP baldor for less than $100, WITH SHIPPING! They're something like 500 new.
 
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Thanks Nathan! I'm not sure where my grandpa got the bearings that are on the lathe.:dunno: The bearings that I added for the jack shaft came with the 1/4HP motor I found for $5 at an estate sale. It was rigged with a buffing wheel and a wire brush when I bought it. The speeds according to a spreadsheet I found online should be somewhere around 345, 430, 575 and 860. Before my low speed was about 690 (I thought it was lower:eek:) so I'm very excited to spend some "quality" time on the lathe again.

As to the motor, I think the capacitor might be the problem from discussions I've had with a few people here locally. I'm trying to find time to take it to a repair shop so I can get it on the lathe asap.
 
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